Because of the manifestations of the Epstein-Barr Virus (EBV) in the normal and immunosuppressed host (fulminant lymphoproliferative syndrome versus malignant lymphoma-like lesions versus typical, acute infectious nomonucleosis) and the known association of EBV with African Burkitt's lymphoma and nasopharn- geal carcinoma, we have been conducting a diversified investigation into the role of EBV high-risk patients who are enrolled in the AIDS vaccine study. The EBV isolated from the lymph nodes and PBLs from a moderate percentage of both AIDS as well as chronic mononucleosis patients appears to be different from that described in the literature. These isolates are capable of both inducing EA in Raji cells and transforming human cord blood lymphocytes. The transformed cord blood cells in many instances themselves became virus producers for a short period of time. These findings suggest AIDS patients are predisposed to EBV associated disease and may in many cases harbour a relatively undescribed form of the virus. This virus may also be involved in EBV associated aplastic anemia as in recent studies patients with history of active EBV infection demonstrated bone marrow cells as well as PBLs to be 3 - 5% EBNA positive. This has been confirmed by positive DOT and Southern blot against EBV suggesting this virus may be highly implicated in certain types of aplastic anemia. Peripheral leukocytes from an Epstein-Barr associated aplastic anemia patient were used to establish an IL2 dependent cell culture (JR), JR cells are CD4 positive by FAC's analysis and remain IL2 dependent after six months in culture. JR cells produce an HTLVII like virus as determined by electron microscope reverse transcriptase, PCR and nucleic acid analysis. Both PCR and Southern blotting analysis of probes were used. The study is in progress.